cli: Enables using modern hush parser as command line parser

If one defines HUSH_MODERN_PARSER, it is then possible to use modern parser with:
=> cli get
old
=> cli set modern
=> cli get
modern

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Francis Laniel <francis.laniel@amarulasolutions.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 15715ac..e25578c 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -33,6 +33,18 @@
 	  2005.
 
 	  It is actually the default U-Boot shell when decided to use hush as shell.
+
+config HUSH_MODERN_PARSER
+	bool "Use hush modern parser"
+	help
+	  This option enables the new flavor of hush based on hush upstream
+	  Busybox.
+
+	  This parser is experimental and not well tested.
+
+config HUSH_SELECTABLE
+	bool
+	default y if HUSH_OLD_PARSER && HUSH_MODERN_PARSER
 endmenu
 
 config CMDLINE_EDITING